English to Hebrew Bus/Financial Business/Commerce (general) General

I need this margin:
In a general business context, the difference between a product's (or service's) selling price and the cost of production.
Gross profit **margin** (which is the difference between revenue and expenses) is one measure of a company's performance.

http://www.investopedia.com/terms/m/margin.asp

Please note the different types of margins (in the link) when you make your suggestion.
My context is general, not aimed at pros.
I was thinking of רווח שולי but my text doesn't say profit margin, it says excessive margin.